1. Field of the Invention
This invention relates to a fire retardant polyolefin plexifilamentary film-fibril strand and sheet made therefrom. This sheet can be used in, for example, a flame retardant building substrate, garment, banner, light reflector and cover.
2. Description of the Related Art
Polyolefins, e.g., polyethylene and polypropylene fibers, are high volume/low cost synthetics that are remarkable for their stain and abrasion resistance. As with all plastics, certain uses have required that the flammability of the polymer be reduced. When decreased flammability has been required, it has generally not been provided by the polyolefin fiber itself, but has instead been provided by one of the other components in the fabricated article.
Polyolefin plexifilamentary film-fibril strands can be made into a sheet which has been used in many end uses, for example, a building substrate, garment, banner, light reflector and cover.
Although flame retardant coatings have been used, a flame retardant that can be spun directly into the fiber would offer advantages in durability and potentially cost.
A flame retardant plexifilamentary fiber strand was made from a mixture of polyesters, a polyester elastomer and a fire retardant via flash spinning from a spin agent of carbon dioxide and water as disclosed in U.S. Pat. No. 6,096,421. However, the plexifilamentary fiber strand had poor mechanical properties.
It would be desirable to make a sheet made from a flame retardant polyolefin plexifilamentary film-fibril strand that does not suffer from the aforementioned disadvantages.